Plug contactor



July 31, 1956 w. s. wA'r'rs PLUG CONTACTOR Filed Aug. 5, 1953 T. l. ,2 20b 2Q a 20GZ wmw lZa

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William .15. Winas I wwwig United States Patent PLUG CONTACTOR William S. Watts, Harrisburg, Pa., assignor to Aircraft- Marine Products, Inc., Harrisburg, Pa., a corporation of New Jersey Application August 5, 1953, Serial No. 372,482 7 Claims. (Cl. 339-91) This invention relates to plug contactors of the type used, for example, in plugboards for automatic computers, tabulators, accounting machines and the like, which may be withdrawn from the plugboard by pulling the electrical conductor to which the plug is attached but which may not normally be pushed from the plugboard by pressure on the nose of the plug.

It is among the objects of the present invention to provide a plug of the type described which is simpler and more economical in construction than previous plugs of this type. It is also an object of the invention to provide such a plug which is rugged enough to withstand rough handling and which has a long useful life.. Another object is the provision of a plug which can be pushed from the plugboard by pressure on the nose of the plug, but which requires a substantially greater force to accomplishthis than is required for pulling the plug from the plugboard. A further object is that of providing a plug which may be assembled easily but which is not subject to accidental disassembly during use or handling. Other objects of the invention will be in part apparent and in part pointed out hereinafter.

In the drawings:

Figure 1 is a longitudinal sectional view of a plug embodying features of the present invention, with the plug being shown in fully inserted position in a plugboard;

Figure 2 is a transverse sectional view, at slightly enlarged scale, taken generally along the line 2-2 of Figure 1;

Figure 3 is a fragmentary longitudinal sectional view showing the plug in partially withdrawn position with respect to the plugboard; v

Figure 4 is a side view, partially in section of an alternative form of plug embodying features of the invention;

Figure 5 is'a transverse sectional View, at.slightly enlarged scale, taken generally along the line 55 of Figure 4; and,

Figure 6 is a fragmentary longitudinal sectional view of the plug of Figures 4 and 5, with the plug being shown in partially withdrawn position with respect to'the plugboard.

The plug shown in Figures 1-3 comprisesa hollow cylindrical sleeve 10 of a conductive metal, suitably nickelplated brass which is rolled up from flat sheet stock into tubular form with a butt seam 102 (Figure 2) extending longitudinally of the sleeve along its bottom center line. The sleeve 10 is attached at the rearward end of the plug (the right-hand end as viewed in Figures 1 and 3) to an insulated wire 12. The rearward end portion of the sleeve 10 is formed into a ferrule 10a initially of the cross-sectional shape of an inverted U. The insula-' tion 12a is stripped from the end portion of the insulated wire 12 and the bare end of the inner conductor 12b is received in the ferrule 10a. This assembly is then crirnped by means of dies which bend the tabs at either side of the ferrule around the wire and drive their ends generally axially into .the stranded conductor 12b and 3 finally compact the ferrule 10a and conductor 12b into a substantially solid mass. This not only results in an excellent electrical connection between the conductor 12b and the sleeve 10, but produces a connection of suflicient mechanical strength to withstand the tensile stresses to which the conductor and sleeve ,will be subjected in normal use.

An insulating sheath 18 of a suitable resin, for example polyvinyl chloride, is molded onto the rearward end of the sleeve 10 and the adjacent portion of the insulated wire 12. This sheath 18 not only electrically insulates the end portion of the sleeve 10 but supports the insulated wire 12 adjacent the sleeve and increases its resistance to bending fatigue, while affording a convenient grip by which the rear end of the plug may be grasped for inserting the plug into or withdrawing it from the plugboard. The sleeve 10 is provided with an outwardly projecting crimp 10d near the forward end of the insulating sheath 18 to tie the sheath 18 to the sleeve 10.

In Figure 1, the plug is shown in fully inserted position in a plugboard 20 which is provided with a number of cylindrical openings such as 20a each of which is adapted slidably to receive the sleeve 10 of a plug. The forward end of the insulation sheath to limit the movement of the plug into the plugboard.

When the plug is in the fully inserted position as shown in Figure 1, the forward end of the sleeve 10 is conductively engaged by a spring contact 22 within the electrical device with which the plugboard is used, in order to complete a selected electrical circuit.

The forward end of the sleeve 10 is open and init is slidably received a nose member 24, which is suitably formed of a relatively stiff, resiliently flexible plastic such as nylon. The forward end of the nose member 24 is tapered to facilitate insertion of the plug into the plugboard.

The portion of the nose member 24 within the sleeve 10 is divided generally into three sections: a forward section 24a which is cylindrical in shape and is dimensioned so as to fit snugly within the sleeve 10 and support the forward end of the nose member, a rear section 24b which engages one side of the inner surface of the sleeve 10 to support the rear end of the nose member, and an intermediate section 240 of reduced cross-sectional area which is provided at one side with a spherically concave v cup 24d for cradling a spherical latch member or ball 26 of steel or other hard material. The ball 26 is received.

in an opening 10b in the sleeve 10 which is small enough to prevent the ball from falling out or being pushed out of the sleeve 10, but large enough so that the ball 26 can project through the opening to an outer position,

shown in Figure l, slightly beyond the outersurface of the sleeve 10.

The ball 26 is normally maintained in this outer position by the nose member 24. However, because of the resilient flexibility of the relatively thin intermediate section 240 of the nose member and because the intermediate section 24c is recessed as indicated at 24e so that it is spaced from the inner surface of the sleeve 10 on the side opposite the opening 10b by a distance at least equal to the distance by which the ball 26 projects beyond the outer surface of the sleeve 10, the ball 26 may be depressed at least to an inner position shown in Figure 3 wherein it is substantially flush with the outer surface of the sleeve 10, thereby permitting the plug to be inserted into or withdrawn from the plugboard 20.

' tion of the plug,

Because the forward and rearward surfaces of the por tion of the ball 26 which projects beyond the sleeve 10.

18 acts as a stop portion of the ball 26 engages the front face of the plugboard 20 adjacent the opening 20a and the ball 26 is cammed inwardly, bowing or springing down the resiliently flexible intermediate section 240 of the nose memher, to the point where the ball is substantially hush with the outer surface of the sleeve 10, thereby permitting the plug to be inserted into the pl-u'gboa-rd. 'When the plug has been inserted fully into the plugboard, the bail-126 will spring back wardly to the position shown in Figure l, at which it is engaged behind the rear surface 20b of the plugboard.

With the plug in the fully inserted position in the plugboard, a rearward pull on the conductor 12 or insulation sheath 1-8 will move the sleeve 10 rearwardly (to the right as viewed in Figures 1 and '3), causing the portion of the ball 26 which projects through the opening 1'07) in the sleeve to be squeezed between the forward edge of the opening 1'01) and the corner 20c of -'the plu-'gboard between its rear face 20b and the opening 200. This produces a double camm-in'g action in which the "forward edge of the opening 10b in the sleeve acts upon the inclined forward surface of the ball 2'6 and the corner 20c acts upon the inclined rearward surface of the ball 26. The ball is thus readily carnnred inwardly against the resistance of the resilie'ntly flexible intermediate portion 24c of the nose member, as shown in Figure 3, to the point where the ball is substantially flush with the outer surface of the sleeve 11), thereby permitting the plug to be withdrawn from the plugboard.

With the plug in the fully inserted position, a rearward pusho'n the forward end f the plug, i. e., upon the nose member 24, will te'ndto produce a rearward movement of the nose member '24 relative to the sleeve ll). This will cause the upwardly inclined sur'face 24f of the nose memher to "engage the forward surface of the ball 26 and, as indicated by the oblique broken line 28, press the ball 26 against the corner 20c of the plugboard. Because of the inclination of the rearward surface of the ball '26 at its point o'f engagement with the corner 200, there is a te'ndency for the ball 26 to be cammed inwardly. However, because the rearward pressure on the nose member '24 brings into carnming action only the rear surface of the ball and the corner 20c, and not the forward surface of the ball and the forward edge of the opening b in the sleeve, as does arearwar-d pull on the sleeve 10, 'a greater force is required to push the plug out of the plugboard than is required to pull the plug out of the plu'gbba'rd.

Therequireinent of 'am'oderately high pressure for pushing'the plug from'the plugboard tends to prevent the plug from being pushed accidentally from the plughoa'rd, as, for "example, when the p'lugb'oard is placed front-side-up on a table and supported by the projecting noses of the plugs, while preventing damage to the plug "by the fa 'p'p1icationof aninor'dinately'hig'h pressure on its nose, as when theplugboard is accidentally dropped.

The sleeve [0 is provided with an inwardly projecting boss or dimple 10c opposite the recess Me of "the 'nose member. This boss 10c limits the extent to whichihe intermediate portion 240 of the nose member may be bowedor 'sprung'down'wardly and thereby limits the extent to which the ball 26 may be depressed. 'The boss 10c projects into the sleeve 10 'forsuch distance "as to'p'ermit the ball 26 to be depressed at least to the extent where itis substantially hush with the'outcr surface of the sleeve 10 but not to the extent where it would be 'ilush with the inner surface of the sleeve. The boss 100 thus prevents the nose member 24 from being pushed "into the sleeve past the point at which the ball 26 projects through the opening 10b, and prevents the nose "from being accidentally withdrawn from the sleeve. To facilitate initial assembly of the plug, the 'boss 100 is no'tfor'm'ecl until the nose member 24 and 'the ball 26 have 'bee'ninserted into proper po'sitionin the sleeve 10.

"Sincethe portion of the plug which is most likely to break ofi'or'shear off or to be abraded or otherwise worn or damaged in usei. e. the latch member or ball 26- is a separate piece which is formed of steel or a similar hard material, the plug is relatively invulnerable to damage and has a long useful life.

The embodiment of the plug which is shown in Figures 4-6 is generally similar in operation to that just described, including a sleeve 30 and a nose member 32 which is slidably received therein and projects from the forward end thereof. The nose member 32 is generally divided into three sections, including forward-and rear sections 32a:and 32b respectively, which fit the internal dimensions of the sleeve 30 to support the nose member 32 within the-sleeve, and an intermediate section 32c of reduced cross sectional area which extends obliquely across the interior of the sleeve 30 between the forward and rear sections. As shown in Figure 5, the intermediate section 32c of the nose member is provided with a cylindrical groove 3211 for cradling a latch member 34 in the form of an elongated cylindrical rod '34 of a relatively hard material such as a phenolic resin, or metal. The rod '34 extends along the intermediate portion 320 of the nose member and obliquely projects partially through an opening 39a in the sleeve '30 in position to be engaged behind the rear face 207: of the plu'gboard when the plug is in fully inserted position 'in one of the openings 20a of the plugboard. The reduced cross-sectional area of the intermediate portion 32c of the nose member 32 makes it resiliently flexible so that the rod 34 may be depressed or tipped to reduce its inclination with respect to the axis of the sleeve 30 to the extent shown in Figure 6 wherein the outermost portion of the rod 34 is substantially flush with the outer surface of the sleeve 30 to permit the plug to be inserted into or withdrawn from the plugboard '20.

The rearward end 34a of the rod 34 is conical in shape and the corner 20c of the 'plugboard engages the rearward end 34a at 'a point above the axis of the rod 34, so that a force tending to move the rod 34 rearwardly with respect to the plug'board 20 tends to cam the rearward end of rod inwardly. Also, because of the inclination of the rod 34, a rearward force directed against the forward surface 34b of the rod, such as occurs when the plug -is inserted into the plugboard 20, will cause .the rod to "be cammed inwardly.

As in the embodiment previously described, a rearward pull on the conductor 12 or insulation sheath '18 will produce a double camrn'in'g action involving not only the rearward end 34a of the rod 34 and the corner 200 of the plugboard 2.0, but also the inclined forward surface 34b of the rod and'the forward edge of the opening 30a in the sleeve '30 so that the plug may be withdrawn from the plugboard by a relatively light pulling force. However, a rearward pushing force imposed upon 'the3forward end of the nose member 32 will bring into cammiug action only the rearward end 34a of the rod 34 and the corner 200 of the plugboard so'that a substantially greater force is required to push the plug from the plugboard than that which is required to pull the plug from the plugb'oard.

The inclination of the forward sur'face 34b of the rod is sufficiently steep that after the sleeve has been pulled re'a'rwardlfy, as shown in .Figure 6, to withdraw the plug from the plugboard, the rod 34 can spring back to its outer position, drawing the nose member back 'into proper longitudinal position within the sleeve.

In order to prevent accidental withdrawal of the nose member 32 and .rod 3 1 from the sleeve'3'0, an inwardly projecting flange 3012 is punched in the sleeve 11) at a point just forward of the rear section 52b of the nose member imposition to engage the rear section 321) and limit movement of the nose member .32 relative to the sleeve. 30. 'To facilitate initial assembly of the plug, the flange 30b 'is not stamped in the sleeve until the nose member 32 and rod '34 have been inserted into proper position within the sleeve '30.

'Frorn the foregoing description it will be understood that the present invention provides plugs having only a few inexpensive parts which may readily be assembled. In each embodiment of the plug, the latch member is formed of a material of high mechanical strength so that the latch is not readily worn away by repeated insertion and Withdrawal of the plug, nor is it apt to be sheared off by the application of an inordinately high force on the plug. It will therefore be appreciated that the aforementioned and other desirable objects have been achieved. However, it should be emphasized that the particular embodiments of the invention which are shown and described herein are intended as merely illustrative and not as restrictive of the invention.

I claim:

l. A plug contactor comprising an elongated hollow sleeve adapted for conductive attachment at its rearward end to a wire conductor, a rigid latch member in said sleeve with a portion of said latch projecting through an opening in said sleeve to an outer position beyond the outer surface of said sleeve, the forward and rearward surfaces of the portion of said latch member projecting beyond said surface and sloping with respect thereto to provide cam surfaces on the projecting portion of said latch member operatively cammed inwardly by a longitudinal force along said surface, and a resilient nose member slidably received within said sleeve and projecting from the forward end thereof, said nose member having an intermediate portion supporting said latch memher, said intermediate portion being resiliently flexible for urging said latch member to said outer position and resiliently flexing in a transverse direction to permit said latch to be depressed at least to an inner position at which it is substantially flush with the outer surface of said sleeve.

2. A plug contactor as claimed in claim 1 wherein said latch member is formed of metal and said nose member is formed of a synthetic resin.

3. A plug contactor comprising an elongated hollow sleeve adapted for conductive attachment at its rearward end to a wire conductor, a generally spherical latch mentber in said sleeve projecting through an opening in said sleeve of lesser width than the diameter of said latch member to an outer position beyond the outer surface of said sleeve, and a resilient nose member slidably received within said sleeve and projecting from the forward end thereof and having within said sleeve spaced sup porting portions engaging the inner surface of said sleeve on the side opposite said opening and an intermediate portion supporting said latch member and urging the same toward such outer position, said intermediate portion being resiliently flexible and being spaced from the inner surface of said sleeve on the side opposite said opening by a suflicient distance to permit said latch member to be depressed at least to an inner position substantially flush with the outer surface of said sleeve.

4. A plug contactor comprising an elongated hollow sleeve adapted for conductive attachment at its rearward end to a wire conductor, an elongated latch member projecting through an opening in said sleeve at an angle with the axis of said sleeve, said opening being of such dimensions that said latch member cannot pass completely through said opening at said angle, the forward and rearward surfaces of the portion of said latch member projecting beyond said surface being inclined with respect thereto to cause said latch member to be cammed inwardly by a longitudinal force along said surface, and a resilient nose member slidably received within said sleeve and projecting from the forward end thereof and having within said sleeve spaced portions engaging the inner surface of said sleeve on the side opposite said opening for supporting said nose member in said sleeve and an intermediate portion normally supporting said latch member at said angle and being resiliently flexible and being spaced from the inner surface of said sleeve on the side opposite said opening by a sufiicient distance to permit said latch member to be tipped to a lesser angle with respect to the axis of said sleeve at which said latch member is substantially flush with the outer surface of said sleeve.

5. A plug contactor comprising an elongated hollow sleeve adapted for conductive attachment at its rearward end to a wire conductor, an elongated cylindrical latch member projecting through an opening in said sleeve at an acute angle with the axis of said sleeve, said opening being of such length that said latch member cannot pass completely therethrough at said angle, and a resilient nose member slidably received within said sleeve and projecting from the forward end thereof and having within said sleeve spaced portions engaging the inner surface of said sleeve on the side opposite said opening for supporting said nose member in said sleeve and an intermediate portion cradling said latch member and normally supporting the same at said angle and being resiliently flexible and being spaced from the inner surface of said sleeve on the side opposite said opening by a suflicient distance to permit said latch member to be tipped to a lesser angle with respect to the axis of said sleeve at which said latch member is substantially flush with the outer surface of said sleeve.

6. A plug contactor comprising an elongated hollow sleeve adapted for conductive attachment at its rearward end to a wire conductor, a rigid latch member in said sleeve with a portion of said latch projecting through an opening in said sleeve to an outer position beyond the outer surface of said sleeve, the forward and rearward surfaces of the portion of said latch member projecting beyond said surface and sloping with respect thereto to provide cam surfaces on the projecting portion of said latch member operatively cammed inwardly by a longitudinal force along said surface, a resilient nose member slidably received within said sleeve and projecting from the forward end thereof, said nose member having an intermediate port-ion supporting said latch member, said intermediate portion being resiliently flexible for urging said latch member to said outer position and resiliently flexing in a transverse direction to permit said latch to be depressed at least to an inner position at which it is substantially flush with the outer surface of said sleeve, and a projection extending from the inner surface of said sleeve cooperating with an abutment on said nose member for stopping withdrawal of said nose member from said sleeve.

7. A plug contactor substantially as set forth in claim 6 wherein said projection is disposed substantially opposite said sleeve opening and having a height eifective to limit depression of said latch member to less than a flush position with the inner surface of said sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 574,281 Scribner et al. Dec. 29, 1896 1,864,989 Maag-Eckenfelder June 28, 1932 2,330,948 Brand et al Oct. 5, 1943 2,624,774 Cunningham Jan. 6, 1953 

